The agent is not installed, or is installed and working correctly, but the Altiris Agent Installation service is listed multiple times in the Windows Service Manager, similar to the following. This is also shown with the agent icon disappearing and re-appearing.
The agent was pushed multiple times (most likely due to the resource not being removed from the targeted collection) and the Altiris Agent Install Service was never removed. This can also be caused if the machine has a corrupt account in Active Directory.
Many times just rebooting the machine will fix the issue if the agent is installed and working.
Remove the machine from the AD domain and re-add them if the agent is not installed correctly. (This is due to a corrupt AD computer account for the PC.)
Do a manual uninstall of the Altiris Agent then install again:
Run the following command line to remove the Altiris Agent using AeXAgentUtil.exe located by default at